Chemical bonding of rubber to plastic in articles of footwear

ABSTRACT

An article of footwear comprising relatively elastic and relatively inelastic materials chemically bonded together is disclosed. In one embodiment, the relatively elastic and relatively inelastic materials are arranged in such a fashion to impart flexibility to the article of footwear. In particular, plastic and rubber materials are bonded together to improve the flexibility of an outsole of an article of footwear. The invention also is directed to the fabrication of new or improved devices and elements for use in articles of footwear and their associated methods of construction such as closure mechanisms comprising relatively elastic straps bonded to relatively inelastic anchor portions and vice versa, articulating inelastic and elastic exoskeleton constructions useful in skates and ski boots, and elastic or inelastic eyelets surrounded by inelastic or elastic materials. The invention also is directed to chemically bonding relatively elastic to relatively inelastic materials for contemplated use in protective athletic equipment such as helmets and protective padding, and for use in prosthetic devices.

RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 07/986,046, filed on Dec. 10, 1992, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the formation of a chemical bond betweenrelatively elastic and relatively inelastic materials, for example,between rubber and plastic materials. In particular, the inventionrelates to an outsole of an article of footwear and methods of makingthe outsole wherein the outsole comprises both relatively elastic andrelatively inelastic materials which are chemically bonded together.

2. Prior Art

Elastic and inelastic materials have been used in the construction ofarticles of footwear for many years. Particularly, rubber materials havebeen widely used in the fabrication of midsoles and outsoles of articlesof footwear. Rubber and plastic elements frequently are placed in directcommunication with one another in the fabrication of an article offootwear with conventional fixation methods including stitching,riveting, screwing, nailing, and the use of various adhesives.

The use of adhesives has numerous disadvantages. Adhesives often arevolatile and harmful to the environment both in the emission to theatmosphere of noxious gases and in the emission to the surroundingenvironment of the adhesives and their by-products. Adhesives alsotypically do not form a favorable bond between the rubber and plasticand hence, the materials are prone to rip and tear when the adhesivebond fails.

The use of adhesives also often requires the labor intensive steps ofroughing at least one of the material surfaces to be joined, applyingprimer and adhesive, fitting the components, and applying both heat andpressure in order to activate the cement system and form a mechanicalbond between the adjoining rubber and plastic materials. This process istime consuming, labor intensive, expensive, and presents numerousopportunities for human, material, or environment variables to adverselyinfluence the quality of the mechanical bonds and associated products.The adhesive bond formed is prone to delamination of plastic and rubberas the result of bond failure induced by fatigue and environmentaldegradation.

Direct injection of plastic and rubber to one another, to leather, andto many of the natural and synthetic textiles commonly used in themanufacture of articles of footwear also is known. See U.S. Pat. No.4,481,727 to Stubblefield (double pour mold or double density injectionprocess). Direct injection also has its disadvantages in that itcommonly employs heat, pressure, various primers, and the technique ofimpregnating textiles with the plastic and/or the rubber material inorder to enhance the quality of what is nevertheless substantially amechanical bond formed between the elements. The mechanical bond formedby direct injection also is prone to delamination of plastic and rubberas the result of bond failure induced by fatigue and environmentaldegradation.

The formation of a chemical (covalent) bond between specific rubber andplastic articles is known and described in U.S. Pat. Nos. 4,816,345 and4,921,762 to Jadamus et al. U.S. Pat. No. 4,816,345 discloses thebonding of a molded piece of a polyphenylene ether-containing polymerand a molded piece of an elastomeric thermoplastic block copolymer ofthe type A-B-A, wherein A represents a styrene block and B represents asoft phase block, for example a block of polymerized conjugated dienewhich may or may not have been selectively hydrogenated. The bonding isachieved by heating of the two pieces while contacting each other. Thebonding mechanism is not known, but is distinguished from vulcanization.U.S. Pat. No. 4,921,762 disclose a process for bonding a thermoplasticpolyphenylene-ether-containing polymer and a rubber (EPDM and/orstyrene-butadiene rubber) by covulcanization, wherein the rubber portioncontains peroxidic vulcanization agents and vulcanization activators.Additionally, in the background thereof, it is disclosed as known thatSBR and EPR rubbers and polybutadienes have high adhesion topolysulfones, polycarbonates and certain polyphenylene ethers after athermal treatment.

Further, vulcanization is known is the art as a means of attaching shoeportions to each other. U.S. Pat. No. 4,130,947 to Denu discloses anoutsole layer extending across the entire bottom of the shoe which hasbeen vulcanized to a softer midsole layer. U.K. Patent Specification No.298,718 to Looms et al. discloses vulcanizing a separate forefoot treadmember and a heel tread member to a sole base or foundation. U.S. Pat.No. 4,676,010 to Cheskin discloses a sole having a plurality ofdiscontinuous and independent outsole pieces attached to the lowersurface of the midsole by vulcanization. The exposed lower surface ofthe midsole is asserted as making a significant contribution to theflexibility and weight reduction of the sole. However, because of thechemical make up and the dissimilar properties of rubbers versusthermoplastics and thermoplastic elastomers, vulcanization of one to theother without pretreatment of one or both substrates cannot effectivelybe achieved.

The aforementioned methods of chemically bonding rubber and plastictogether typically utilize expensive machinery, and specific rawmaterials. In the footwear industry, in particular, manufacturing costis of paramount concern. Thus, there is a need in the art for reductionof costs of production including improving efficiency of manufacture anddecreasing the cost of raw materials.

It is generally known that the use of grooves in the outsole of anarticle of footwear improves the flexibility of the sole. See U.S. Pat.No. 4,562,651 to Frederick. U.S. Pat. No. 5,012,597 to Thomasson alsodiscloses that the grooves reduce the thickness of the sole bottom attheir locations and render the sole easier to bend at the locations ofthe grooves in the direction perpendicular to the grooves. The formationof grooves in the outsole and/or midsole for an article of footweartypically entails additional manufacturing or processing steps or theuse of special molds designed to include the grooves. Thus, there existsa need to provide for enhanced flexibility in an outsole for an articleof footwear which does not require the use of grooves.

U.S. Pat. No. 5,024,007 to DuFour discloses that a walking sole for agolf shoe which comprises an outsole comprised of a relatively rigidmolded plastic material and an elastic plastic material has improvedlongitudinal flexibility and a greater degree of transverse rigidity.The elastic plastic material fills notches and elongated openingspresent in the relatively rigid molded plastic material. Outsolescomprised entirely of plastic materials typically are inappropriate formost articles of footwear, i.e., athletic footwear such as shoes forrunning, basketball, tennis, racquetball, etc. The excess rigidity,weight and lack of traction render outsoles comprised entirely ofplastic materials undesirable for use in most athletic footwear.Outsoles comprised entirely of rubber materials for articles of footwearcan lack necessary support.

Thus, there also exists a need to formulate an article of footwear whichcomprises an outsole having various physical and mechanical propertiesin different regions, and wherein these regions are adequately bonded toone another. There exists a need to provide an outsole for use in anarticle of footwear which has greater flexibility, less weight and hassufficient durability. Additionally, there is a need to provide anefficient and economical method for bonding relatively elastic andrelatively inelastic materials for use in an article of footwear withoututilizing adhesives.

SUMMARY OF THE INVENTION

The invention is directed to an article of footwear comprisingrelatively elastic and relatively inelastic materials chemically bondedtogether. In one aspect of the invention, plastic and rubber materialsare bonded together to improve the flexibility of an outsole of anarticle of footwear. The invention also is directed to the fabricationof new or improved devices and elements for use in articles of footwearand their associated methods of construction such as closure mechanismscomprising relatively elastic straps bonded to relatively inelasticanchor portions and vice versa, articulating inelastic and elasticexoskeleton constructions useful in skates and ski boob and elastic orinelastic eyelets surrounded by inelastic or elastic materials,respectively. The invention also is directed to chemically bondingrelatively elastic to relatively inelastic materials for use inprotective athletic equipment such as helmets and protective padding,and for use in prosthetic devices.

In accordance with one aspect of the present invention, relativelyelastic and relatively inelastic materials are chemically bondedtogether to improve the flexibility of outsoles for use in articles offootwear. Specifically, rubber and plastic materials are chemicallybonded together to form flex lines or segments in the outsole. The flexlines or segments typically comprise the rubber component, and theremainder of the outsole comprises the plastic component. The rubber andplastic materials also may be arranged and chemically bonded to form anoutsole having various configurations of the components so that improvedflexibility is attained. The materials also may be arranged so thattraction elements are present on the outsole. The relatively elastic andrelatively inelastic materials also may be chemically bonded to formenclosure devices such as straps, eyelets, exoskeleton structures foruse in skates and ski boots, heel plates, as well as other variousfunctional applications on articles of footwear requiring or benefittingfrom the interplay of relatively elastic and inelastic materialschemically bonded to each other.

The articles of footwear made in accordance with the present inventionare easy to manufacture, have reduced costs due to ease of manufactureand reduced amounts of raw materials, minimize or eliminate the use ofadhesives, have improved flexibility and improved adhesioncharacteristics when compared to articles of footwear comprising plasticand rubber elastic materials bonded by conventional adhesives. These andother various features, advantages and objects of the present inventionwill be apparent from the following detailed description of theembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a "v-flex" footwear outsole showing the use ofrubber bonded to and joining adjacent plastic outsole segments whereinthe rubber flex lines form a v-shape and replace the "v-grooves" of theprior art.

FIG. 2 is a cross-sectional view of the footwear outsole shown in FIG. 1along line A--A showing rubber material extending between independentsegments of plastic outsole plate material.

FIG. 3 is a plan view of a footwear outsole showing the use of rubberbonded to and joining three plastic outsole segments forming rubber flexlines located about and underlying the ball of the foot in the area ofthe forefoot.

FIG. 4a is a plan view of a footwear outsole plate located about andunderlying the forefoot showing rubber bonded to and joining adjacentplastic outsole segments forming rubber flex lines about both themedial-to-lateral or transverse axis and the anterior-to-posterior orlongitudinal axis.

FIG. 4b is like FIG. 4a and further shows the areas of contact of theforefoot above the outsole depicted.

FIG. 4c is a plan view of an alternate embodiment of a footwear outsoleplate similar to that shown in FIGS. 4a and b.

FIG. 4d is a cross-sectional view of the outsole plate shown in FIG. 4calong line J--J.

FIG. 5 is a plan view of a footwear outsole plate showing rubber bondedto adjacent plastic outsole segments located in the area about andunderlying the heel of the foot forming a rubber flex line along lineI--I therebetween, one of the segments generally corresponding to therearfoot strike zone.

FIG. 6 is a plan view of a footwear outsole showing rubber cleats, ortraction elements bonded to plastic elements of a footwear outsole andv-shaped rubber flex lines along lines B--B and C--C.

FIG. 7 is a plan view of a footwear outsole showing plastic cleats, ortraction element bonded to rubber elements of a footwear outsole andv-shaped plastic flex lines along lines B--B and C--C.

FIG. 8 is a plan view of a footwear outsole showing a rubber segmentlocated in the area about and underlying the midfoot bonded to twoplastic plate portions generally corresponding to and underlying therearfoot and forefoot areas.

FIG. 9 is a plan view of an alternate embodiment of a "v-flex" footwearoutsole showing the use of wedge-shaped rubber segments bonded to aplastic outsole at corresponding wedge-shaped notches therein so as toenhance the flexibility of the footwear outsole in at least one selectarea and along at least one select line of flexion such as lines B--Band C--C.

FIG. 10 is a plan view of a footwear outsole showing two segments ofrubber bonded to a plastic outsole plate that are substantially locatedabout the medial and lateral aspects of the area of the footwear outsoleunderlying the midfoot.

FIG. 11 is a plan view of a footwear outsole plate showing a rubbersegment inserted into a corresponding void in a plastic outsole plateand bonded thereto along the perimeter of the rubber segment in the areaabout and underlying the calcaneus of the foot.

FIG. 12 is a plan view of an approximately three quarter length rubberoutsole affixed to a plastic spike plate which substantially underliesthe area of the forefoot.

FIG. 13a is a plan view of a footwear outsole showing a plastic elementlocated in the area about and underlying the midfoot bonded to at leasttwo rubber outsole elements located about and underlying the area of theforefoot and rearfoot wherein the various segments have inclinedsurfaces to increase their respective bond surfaces.

FIG. 13b is a cross-sectional view of FIG. 13a along line 13b--13b.

FIG. 14 is a lateral perspective view showing a plastic heel counterbonded to a rubber footwear outsole.

FIG. 15 is a lateral perspective view showing a plastic stability devicelocated about the lateral aspect of the midfoot bonded to a rubberfootwear outsole.

FIG. 16 is a lateral perspective view showing an elevated rubber toewrap bonded to a rubber footwear outsole.

FIGS. 17a-c show cross sectional views bisecting various embodiments ofa traction element for footwear showing various configurations forbonding plastic and rubber portions thereof.

FIG. 18 is a lateral view of an article of footwear showing a plasticstability strap bonded to a rubber footwear outsole.

FIG. 19 is a lateral view of an article of footwear showing a plasticstability strap bonded to rubber in the area of the junction of thestrap to a plastic footwear outsole.

FIGS. 20a and b are a posterior perspective view and a partial lateralview, respectively, of an article of footwear showing a rearfoot strapconstruction.

FIG. 21 is a partial plan view of a stability strap showing the use ofplastic and rubber materials in the area about an eyelet for a shoelace.

FIG. 22 is a lateral perspective view showing an articulating hockeyskate boot upper.

FIG. 23a and b are a lateral perspective view and a top plan view,respectively, of a plastic stability element bonded to a rubber footwearoutsole member.

FIG. 24 is a cross-sectional view of a plastic plate which is at leastpartially contained within the midsole of an article of footwear bondedto a rubber footwear outsole member and to the midsole member.

FIG. 25 is a graphical presentation of the results of Example 3 whereinthe flexibility of a bar of plastic was compared to the flexibility of anotched bar of plastic and a bar of plastic to which has been chemicallybonded some rubber material.

DETAILED DESCRIPTION

The present invention is based on the improved flexibility anddurability for articles of footwear that can be attained by chemicallybonding relatively elastic and relatively inelastic materials whichcomprise the chemical constituency of various portions of the footweararticle, for example of the outsole. Moreover, use of hazardous bondingmaterials such as adhesives is minimized or entirely avoided. Thepresent invention also provides for an outsole of an article of footwearcomprising the chemically bonded relatively elastic and relativelyinelastic materials which has reduced thickness so that the resultingshoe is lighter, more flexible and costs less to manufacture.

For example, an advantage of the present invention in an outsoleembodiment versus the discontinuous outsole pieces of Cheskin (U.S. Pat.No. 4,676,010), Cheskin does not disclose or discuss bending ridgedplastic to rubber. Further, Cheskin discloses a continuous midsole withdiscontinuous outsole pieces bonded thereto by vulcanization. On theother hand, in an outsole embodiment of the present invention, theoutsole is a bonded composite of alternating plastic and rubberelements, for example as shown in FIG. 2. This eliminates the groovediscontinuities present in the outsole of Cheskin and therefore improveswear of the outsole, e.g. enhancing the wear in the forefoot of tennisshoes. Further, such a composite outsole can improve traction on somesurfaces, e.g. enhancing traction for basketball shoes by properselection of materials and also by increasing the surface area of theoutsole being used. Further, the continuous outsole can avoid damagingsome surfaces, e.g. clay tennis courts, via sharp edges produced bygrooves such as those presented in the discontinuous outsole of Cheskin.Further, this also produces a less likelihood of tripping resulting fromthe absence of such sharp edges produced by these grooves.

In one aspect of the invention, plastic and rubber materials arechemically bonded together to form an outsole of an article of footwear.For example, the plastic and rubber materials are chemically bondedthrough reactive functional groups either at the terminal ends or in theside chains of the polymeric plastic and rubber materials. The polymericplastic or rubber materials may initially comprise the functionalgroups, or may be modified by reaction with a compound having thedesired functional group to achieve the reactive functionality.

Throughout the specification and claims, the phrases "relativelyelastic" and "relatively inelastic" mean that the materials are elasticand inelastic relative to one another. For example, the two materialsmay be elastic in the traditional sense, but a requirement of thepresent invention is that one of the materials have a greater elasticitythan the other. Thus, relative to one another, one material is"relatively elastic" and the other is "relatively inelastic ".Accordingly, "relatively elastic" and rubber may be used interchangeablyand "relatively inelastic" and plastic may be used interchangeablythroughout the specification and claims.

Any relatively inelastic material may be used in accordance with thepresent invention as long as the relatively inelastic material iscapable of forming a chemical bond with the relatively elastic material.Alternatively, the relatively inelastic materials may be modified toinclude pendent reactive groups which provide this capability. Therelatively inelastic material may be primarily a solid material or maybe foamed or blown using foaming and blowing agents, and may be foamedor blown by methods known in the art.

In particular, relatively inelastic materials useful in the presentinvention are plastic materials which typically have a hardness withinthe range of about 60-98 Shore A, and 25-90 Shore D, per ASTM D-2240.The modulus for desirable plastic plate materials useful in the presentinvention typically is from about 60 kg/cm² at 300% elongation to about375 kg/cm² at 10% elongation, per ASTM D-412. Preferably, the plasticmaterials useful in the present invention have a hardness within therange of about 75-95 Shore A, and 35-80 Shore D, and more preferably,within the range of from about 85-90 Shore A, and 45-75 Shore D. Plasticmaterials with a Shore A ranging from about 65 to about 75 areparticularly useful as outsole materials. Plastic materials with anAsker C ranging from about 45 to about 65 are particularly useful asmidsole materials. Preferably, the modulus of plastic materials usefulin the present invention is within the range of about 80 kg/cm² at 300%elongation to about 350 kg/cm² at 10% elongation and most preferablywithin the range of from about 110 kg/cm² at 300% elongation to about300 kg/cm² at 10% elongation. For example, the prior art discloses thatthe thermoplastic multiblock copolymer elastomers used to make themidsoles typically have a Shore D hardness of from 25-45, preferably30-43. When foamed if greater than 45, these elastomers do not havesufficient flexibility for midsole applications; and if less than 25,they have insufficient weight bearing capability. See U.S. Pat. No.4,984,376 to Walter et al., incorporated herein by reference.

Any relatively elastic material which is capable of chemically bondingwith the relatively inelastic material employed may be used.Alternatively, the relatively elastic materials may be modified toinclude pendant reactive groups which provide this capability. Therelatively elastic material may be primarily a solid rubber material ormay be foamed or blown by incorporation of known chemical or physicalblowing agents. The relatively elastic materials are preferably rubbermaterials, including synthetic and natural rubber materials.

Typically, solid rubber materials useful in accordance with theinvention have a hardness within the range of 30-90 Shore A Durometer,per ASTM D-2240. Preferably, the solid rubber materials have a hardnesswithin the range of from about 40-80 Shore A Durometer, and morepreferably within the range of from about 50-70 Shore A Durometer. Themodulus of solid rubber materials useful in the present invention at300% elongation is from about 10 to about 90 kg/cm², per ASTM D-412.Preferably, the modulus at 300% elongation is within the range of fromabout 20-80 kg/cm², and more preferably from about 30 to about 70kg/cm².

The hardness of a foamed or blown rubber material useful in the presentinvention typically ranges from about 20 to about 90 Asker C Durometer,and the modulus of the foamed or blown rubber typically ranges fromabout 10 to about 90 kg/cm² at 150% elongation, from about 10 to about80 kg/cm² at 200% elongation and from about 10 to about 60 kg/cm² at300% elongation, per ASTM D-412. Preferably, the hardness of a foamed orblown rubber material ranges from about 50 to about 80 Asker CDurometer, and more preferably from about 40 to about 70 Asker CDurometer. Preferably, the modulus of the foamed or blown rubber rangesfrom about 10 to about 80 kg/cm² at 150% elongation, from about 20 toabout 70 kg/cm² at 200% elongation and from about 10 to about 50 kg/em²at 300% elongation. More preferably, the modulus of the foamed or blownrubber ranges from about 20 to about 60 kg/cm² at 150% elongation, fromabout 30 to about 60 kg/cm² at 200% elongation and from about 20 toabout 40 kg/cm² at 300% elongation.

A difference of at least 10 points in hardness between the variousmaterials to be joined by chemical bonding is desired to effectmeasurable and subjectively discernable difference in hardness andflexion. The basis for the "10 points in hardness" depends on thematerial being used. For example, Shore A is used for flexible tosemi-rigid materials; Shore D is used for rigid, mostly thermoplasticmaterials having a Shore A greater than 90; and Asker C is used for softmicrocellular foams and similar materials. However, it is well known tothose skilled in the art that beyond a certain point, certain materialsmay become to soft or too hard to effect such a measurable andsubjectively discernable difference in hardness and flexion.

In accordance with the claimed invention, the relatively inelasticmaterial may comprise a plastic material selected from the groupconsisting of thermoplastic polyurethane, polyamide, polyethylene,nitrile, polyvinyl chloride, ethylene vinyl acetate (EVA), polyester,polycarbonate, polypropylene, polyphenylene ether, styrene, vinyl,PEBAX® (polyether block amide), TYVEC® (polyethylene) TEFLON®(tetrafluoroethylene) and TEDLAR® (fluoropolymers), MYLAR® and MELINEX®(thermoplastic polyesters), HYPALON® (chlorosulfonated polyethyleneelastomer) and LEXANE® (polycarbonates).

Suitable plastic materials include polymers having functional moieties,i.e., polar polymers. The functional moieties render the plasticmaterial reactive with the rubber material which also may comprisereactive pendant functional moieties. Typical polar polymers may beselected from the group consisting of polyamides, thermoplasticpolyesters, thermoplastic polyurethanes, vinyl alcohol polymers, vinylester polymers, nitrile polymers, ionomers and halogenatedthermoplastics. Such polar polymers are disclosed in U.S. Pat. Nos.4,080,357; 4,429,076; 4,628,072; 4,657,970; and 4,657,971, thedisclosures of which are herein incorporated by reference. Polyphenyleneethers and polycarbonates may also be useful. Furthermore, it is to benoted that polar polymers having more than one functional group capableof chemically bonding with the rubber material or functionalized rubbermaterial are within the scope of the invention. Thermoplasticpolyurethane have differing physical characteristics, chemicalproperties and applications (or uses) and accordingly may be referred toas urethane, thermoplastic urethane or polyurethane. The distinctionamong these terms is known to those in the athletic shoe art.

As with other thermoplastics, such plastic materials may be foamed.Exemplary of some of the plastics which have been foamed includepolystyrenes, polyolefins, polycarbonates, polyurethanes, polyesters andaldehyde based condensation resins and the like. See U.S. Pat. Nos.2,959,508; 3,717,559; 3,704,269; 3,753,933; 3,863,000; 4,097,425;4,002,581; 4,226,949; 4,247,652; 4,312,960; 4,588,754; and 4,984,376,the disclosures of which are hereby incorporated by reference.

The rubber materials useful in the present invention may comprisehomopolymers of conjugated diene monomers, copolymers of two or moreconjugated dienes and copolymers of one of the dienes with a monoalkenylarene, preferably wherein the copolymer predominates in conjugated dieneunits. The conjugated dienes preferably comprise from 4 to 8 carbonatoms. Examples of suitable conjugated diene monomers include butadiene,isoprene, 2,3-dimethyl-1,3-butadiene and piperylene. Rubber materialsuseful in the present invention include, but are not limited to,materials selected from the group consisting of styrene butadiene rubber(SBR), styrene butadiene rubber/natural rubber (SBR/NR),ethylene-propylene diene monomer/styrene butadiene rubber (EPDM/SBR),carboxylated nitrile rubber (XNBR), polyisoprene rubber (IR), milliableurethane, polychloroporene (neoprene), bromobutyl rubber,chlorosulfonated polyethylene, thermoplastic rubber, latex, silicone,and other natural and synthetic rubbers. Preferably, the rubber materialis selected from SBR, SBR/NR, EPDM/SBR and XNBR.

Other elastomers useful as rubber materials in the present inventioninclude block copolymers comprising a relatively inelastic or "hard"phase and a relatively elastic or "soft" phase. The preparation of suchblock copolymers is known. See U.S. Pat. Nos. 4,174,358; 4,292,414;4,783,503; 4,795,782; 4,797,447; 4,868,243; 4,868,245; 4,882,384;4,898,914; and 4,906,687, the disclosures of which are hereinincorporated by reference.

The rubber material may be chemically modified to facilitate thechemical bond between the plastic material and the rubber material.Modification of the rubber material typically comprises addition of amodifying agent to the base rubber which imparts functional reactivityto the rubber material. The mode of such addition may be, for example,by means of a surface preparation or by dispersion within the rubbermaterial. The functional reactivity imparted to the rubber material isdue primarily to the incorporation of free hydroxyl, carboxyl, amino,ester, ether and the like linkages of the modifying agent. Typically,the modifying agent reacts with the polymeric backbone of the rubbermaterial but may react with polymeric terminal group(s). For example,maleic anhydride, maleic acid, fumaric acid, and the like may be addedto the rubber to form an adduct with the ethylenic unsaturation presentin the rubber material and impart carboxylic acid functionality to therubber. These polymers, by virtue of the presence of the pendentsuccinic anhydride group, can be reacted under appropriate conditionswith the amide or amine groups of a polyamide to produce a chemical bondbetween the modified rubber and plastic materials. See U.S. Pat. Nos.3,887,527; 4,292,414; 4,427,828; 4,429,076; 4,578,429; 4,657,970; and4,795,782, the disclosure of which are hereby incorporated by reference.

Reactive functionality, for example, carboxyl groups, may beincorporated into the alkenylarene potion of the rubber material, suchas those having no ethylenic unsaturation, or into both the alkenylareneportion and other portions thereof having ethylenic unsaturation. SeeU.S. Pat. Nos. 4,783,503; 4,797,447; 4,898,914; and 4,906,687, thedisclosures of which are herein incorporated by reference.

The rubber material may be foamed or blown by use of foaming or blowingagents. Physical foaming and blowing agents function as gas sources byundergoing a change in the phase state. Suitable physical blowing andfoaming agents may be selected from the group consisting of aliphatichydrocarbons and their chloro- and fluoro-derivatives. Typical foamingand blowing agents may be selected from the group consisting of isomersof pentane, hexane, heptane, fluorocarbons, trichlorofluoromethane,dichlorodifluoromethane, dichlorotetrafluoroethane,monochlorodifluoromethane, methylene chloride, carbon dioxide, water andnitrogen. For example, water is a used as a blowing agent formicrocellular polyurethane. Further, nitrogen is used as a mechanicalblowing agent for thermoplastic foams.

Chemical foaming and blowing agents produce a gas via a chemicalreaction. Suitable chemical foaming and blowing agents may be selectedfrom the group consisting of sodium bicarbonate,dinitrosopentamethylene-tetramine, sulfonyl hydroxides,azodicarbonamide, p-toluenesulfonyl semicarbazide, 5-phenyltetrazole,diisopropylhydrazodicarboxylate and sodium borohydrite. The thermaldecomposition of the foaming or blowing agents can be lowered throughaddition of activators, accelerators, or kickers. Water also may beemployed as a blowing or foaming agent for resilient materials such asurethanes and polyurethanes. The rubber material may be foamed or blownusing the aforementioned foaming and blowing agents by methods known inthe art. The chemical bond may be formed between the plastic and rubbermaterials in accordance with any the following five methods: (1)utilizing plastic and rubber materials already having reactivefunctional groups to facilitate a chemical bond between the plastic andrubber materials; (2) modification of the plastic material toincorporate reactive functional groups to facilitate a chemical bondbetween the plastic and rubber materials; (3) modification of the rubbermaterial to incorporate reactive functional groups to facilitate achemical bond between the plastic and rubber materials; (4) modificationof both the plastic and rubber materials to incorporate reactivefunctional groups for the purpose of producing a chemical bondtherebetween; and (5) adding a bridging compound having reactivefunctional groups which react with the reactive functional groups on theplastic and rubber materials which are non-reactive toward each other.

Modification of the plastic and/or rubber material typically comprisesaddition of functional moieties which ultimately yield pendantcarboxylic acid, amide, hydroxyl and other reactive functional groups tothese materials. Preferred functional groups may be selected from thegroup consisting of an amino group, a hydroxyl group, a thiol group, acarboxyl group, an isocyanide group, an epoxy group, an ether group, analdehyde group, a borane group, a silicon group and groups derivedtherefrom such as a urethane group, an ester group, an amide group, anammonium salt group and a metal carboxylate group. These functionalgroups may be bonded to either the terminals or the side chains of theplastic or rubber polymeric material. These materials may also bemodified by incorporating ethylenic unsaturation which may be activatedduring vulcanization.

Other additives may be added to the plastic and rubber materials.Additives include other rubbers, fillers such as carbon black,processing agents, softening agents, metal fibers, graphite, colorants,accelerators, fumed and precipitated silicas, adhesion promoters and thelike. These additives may be present in conventional amounts.

For illustrative purposes, the following detailed descriptions ofcertain thermoplastics and rubber materials are included herein.Polyamides useful in the present invention typically comprise acondensation product which contains recurring aromatic and/or aliphaticamide groups as integral parts of the main polymer chain, such productsbeing known genetically as "nylons". See U.S. Pat. No. 4,906,687,incorporated herein by reference. These may be obtained by polymerizinga monoaminocarboxylic acid or an internal lactam thereof having at leasttwo carbon atoms between the amino and carboxylic acid groups(α-polyamides), or by polymerizing substantially equimolar proportionsof a diamine which contains at least two carbon atoms between the aminogroups and a dicarboxylic acid (α,ω-polyamides), or by polymerizing amonoaminocarboxylic acid or an internal lactam thereof withsubstantially equimolecular proportions of a diamine and a dicarboxylicacid. Polyamides also may comprise a polycondensate of a dicarboxylicacid and a diamine, a polycondensate of an α-aminocarboxylic acid and apolymer produced by ring-opening polymerization of a cyclic lactam. Theα-polyamide have a terminal amino group and the α,ω-polyamide have twoterminal amino groups which are capable of reacting with a functionalgroup on the rubber material, for example a carboxyl group.

Polyamides which may be used in accordance with the present inventioninclude polyhexamethylene adipamide (nylon 66), polypyrrolidone (nylon4), polycaprolactam (nylon 6), polyheptolactam (nylon 7),polycapryllactam (nylon 8), polynonanolactam (nylon 9),polyundecanolaetam (nylon 11), polydodecanolactam (nylon 12),polyhexamethylene azelaiamide (nylon 69), polyhexamethylene sebacamide(nylon 610), polyhexamethylene isophthalamide (nylon 6iP),polymethaxylylene adipamide (nylon MXD6), polyamide ofhexamethylenediamine and n-dodecanedioic acid (nylon 612), and polyamideof dedecamethylenediamine and n-dodecanedioic acid (nylon 1212). Thesepolymers may be used alone or in combination with one another. Nyloncopolymers also may be used, for example, copolymers of the following:hexamethylene adipamide/caprolactam (nylon 66/6),hexamethyleneadipamide/hexamethylene-isophthalamide (nylon 66/iP),hexamethylene adipamide/hexamethyleneterephthalamide (nylon 66/6T),hexamethylene adipamide/hexamethylene-azelaiamide (nylon 66/69) andhexamethyleneadipamide/hexamethyleneazelaiamide/caprolactam (nylon66/69/6). Particularly preferred nylons include nylon 66, nylon 6, nylon11 and nylon 12, mixtures and copolymers thereof.

The polyamides used in accordance with the present invention typicallyhave a number avenge molecular weight (M_(n)) within the range of about200 to about 50,000. Preferred polyamides are those having number avengemolecular weights of at least 5,000. The melting point of the polyamideused in accordance with the present invention typically is within therange of from about 150° C. to about 270° C., and preferably within therange of from about 150° C. to about 220° C.

Polyesters which can be used in accordance with the present inventiontypically comprise a thermoplastic polyester having an ester linkage inthe molecule, and a polyester having a structure formed bypolycondensation of a dicarboxylic acid with a glycol. See U.S. Pat. No.4,906,687, previously incorporated herein by reference. Polyesters ofthis type are obtained by polycondensing a dicarboxylic acid or a lowerester, acid halide or acid anhydride thereof with a glycol. As thestarting aromatic or aliphatic dicarboxylic acid, there are preferablyused oxalic acid, malonic acid, succinic acid, glutaric acid, pimelicacid, suberic acid, adipic acid, sebacic acid, azelaic acid,1,9-nonane-dicarboxylic acid, 1,10-decane-dicarboxylic acid,1,16-hexadecanedicarboxylic acid, terephthalic acid, isophthalic acid,p,p'-dicarboxyphenyl, p-carboxyphenoxyacetic acid and2,6-naphthalene-dicarboxylic acid. Mixtures of two or more of thesedicarboxylic acids also may be used. Of the above-mentioned dicarboxylicacids, terephthalic acid and isophthalic acid are particularlypreferred.

An aliphatic or aromatic glycol (or diol) is used as the other startingmaterial of the polyester. For example, there can be mentioned ethyleneglycol, 1,3-propane diol, 1,2-propane diol, 1,4-butane diol, 1,6-hexanediol, 1,4-cyclohexane diol, 1,10-decane diol, neopentyl glycol andp-xylene glycol. These glycols may be used singly or in the form of amixture of two or more of them. Of these glycols, alkylene glycolshaving 2 to 10 carbon atoms are preferred, and ethylene glycol and1,4-butane diol are particularly preferred. Particularly preferredpolyesters produced by polycondensation of the dicarboxylic acid withthe glycol are polyethylene terephthalate and polybutyleneterephthalate, and modified products thereof in which the monomer unitsare partly substituted with other monomer units.

From the standpoint of process ability and mechanical strength of thecomposition, the number average molecular weight of the polyester isgenerally 500 to 100,000 and preferably 5,000 to 50,000.

The polymerization method for formation of the polyester used in thepresent invention is not particularly critical, and the polymerizationmay be carried out according to customary procedures. For example, theremay be mentioned a method in which the above-mentioned acid component,for example, terephthalic acid, isophthalic acid, an aliphaticdicarboxylic acid or an ester thereof is subjected to directesterification or ester exchange reaction with at least one memberselected from the above-mentioned glycols one at a time, or stepwise.Polymerization then is conducted. Catalysts, stabilizers, modifiers andadditives customarily used may optionally be added.

Another valuable polyester Which may be used in the present invention isa polylactone obtained by ring-opening polymerization of a cycliclactone such as pivalolactone, β-propiolactone or ε-caprolactone.

The above-mentioned polyesters have hydroxyl or carboxyl groups at theterminal ends of the molecule, and these terminal functional groups maybe rendered unreactive by reaction with a monofunctional alcohol orcarboxylic acid. It is preferred that all or part of the terminal endsof the molecule of the polyester have functional groups capable ofreacting with the functional groups of the rubber material. Thepolyester having these functional groups has a remarkably improvedcompatibility with the rubber material because part of these functionalgroups is reacted with the rubber material. In the present invention,the foregoing polyesters may be used alone or in combination thereof.

The thermoplastic polyester referred to in the present inventionincludes polyesters used as fibers, film or resins, such as polyethyleneterephthalate, low crystalline polyesters having a lower melting point,and polyether-ester block copolymers containing hard segments and softsegments in the molecule.

Thermoplastic polyurethanes which are useful in the present inventionare divided into completely thermoplastic polymers and incompletelythermoplastic polymers according to the synthetic conditions, that is,the molar ratio of the NCO group of the diisocyanate relative to the OHgroup of the starting bifunctional polyol or glycol. More specifically,the polyurethane synthesized in a molar ratio of about 0.95<NCO/OH≦1 isa completely thermoplastic polyurethane, and the polyurethanesynthesized in a molar ratio of about 1<NCO/OH<1.1 is an incompletelythermoplastic polyurethane. As the thermoplastic polyurethane, there maybe mentioned a polyurethane comprising a block of a polyol (polyester orpolyether) and a diisocyanate as a soft segment and a block of adiisocyanate and a glycol as a hard segment.

As the starting polyester diol, poly(1,4-butylene adipate),poly(1,6-hexane adipate) and polycaprolactone may be used, and as thepolyether diol, polyethylene glycol, polypropylene glycol andpolyoxytetramethylene glycol may be used. As the glycol, ethyleneglycol, 1,4-butane diol and, 1,6-hexane diol may be used. As thediisocyanate, aromatic, alicyclic and aliphatic diisocyanates may beused. For example, there may be used tolylene diisocyanate,4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate andisophorone diisocyanate.

Besides the foregoing thermoplastic polyurethanes, polyurethanescustomarily used as foams may be used for the composition of the presentinvention, so far as they have a sufficient compatibility with therubber material in the present invention. From the standpoint ofmechanical characteristics of the composition, it is preferred that thenumber average molecular weight of the thermoplastic polyurethane be1,000 to 500,000. Within this range, preferred ranges are known to thoseskilled in the art for desired applications. For example, the prior artin U.S. Pat. No. 4,627,178 to Sullivan et al. discloses thatpolyurethane elastomers may range from about 1,000 to 10,000, forexample 4,000 to 8,000 for midsole applications.

In the present invention, homopolymers of vinyl esters and olefin-vinylester copolymers, such as polyvinyl acetate, ethylene-vinyl acetatecopolymers and propylene-vinyl acetate copolymers, may be used as thevinyl ester polymer.

The vinyl alcohol polymers which may be used in the present inventioninclude a polymer composed of vinyl alcohol units and a copolymercontaining vinyl alcohol units. The polymer composed of vinyl alcoholunits is a polymer obtained by partially or completely saponifying avinyl ester polymer with an aqueous alkali. In the present invention,various polyvinyl alcohols can be used. An olefin-vinyl alcoholcopolymer is preferably used as the copolymer containing vinyl alcoholunits, and from the standpoint of processability and mechanicalcharacteristics of the composition, an ethylene-vinyl alcohol copolymeris particularly preferred. The ethylene-vinyl alcohol copolymer issynthesized from the corresponding ethylene-vinyl acetate copolymer asthe starting substance. An ethylene-vinyl acetate copolymer having avinyl acetate content of 0.5 to 80 mole % is generally used, and anethylene-vinyl alcohol copolymer obtained by saponifying 10 to 100 mole% of the vinyl acetate units of this ethylene-vinyl acetate copolymer isgenerally used.

Thermoplastic homopolymers and copolymers synthesized by using at least50% by weight of an α,β-olefinically unsaturated mononitrile as theconstituent monomer are preferably used as the nitrile polymer in thepresent invention. As the α,β-olefinically unsaturated mononitrile,there may be mentioned, for example, acrylonitrile, methacrylonitrileand α-bromoacrylonitrile. A mixture of two or more of these monomers maybe used. As the monomer to be copolymerized with the α,β-olefinicallyunsaturated mononitrile, there may be mentioned lower α-olefins such asethylene, propylene, isobutylene, pentene-1, vinyl chloride andvinylidene chloride; monovinyl substituted aromatic hydrocarbons such asstyrene, α-methylstyrene, vinyltoluene, chlorostyrene and methylstyrene;vinyl esters such as vinyl acetate; lower alkyl esters ofα,β-olefinically unsaturated carboxylic acids such as methyl acrylateand methyl methacrylate; and vinyl ethers such as vinyl methyl ether.

Another preferred modified plastic material useful in accordance withthe present invention comprises a polyphenylene ether based on2,6-dimethyl-1,4-phenylene ether as the polymeric constituent which ismodified by addition of polyalkenylenes and styrene polymers, and ischaracterized by its amorphous structure which causes it to shrink lesson processing, and has a reduced tendency to warp, as disclosed in U.S.Pat. No. 4,921,762, incorporated herein by reference.

The polyphenylene ethers can be produced from 2,6-dimethylphenol, forexample, in the presence of complex forming agents such as copperbromide and morpholine as described in DE-OS 32 24 692 and DE-OS 32 24691. Typically, the polyphenyene ethers are added as a powder or agranular material.

Polyalkenylenes added to the polyphenylene ether typically are producedby ring opening or ring expansion polymerization of cycloalkenes asdescribed in K. J. Irvin, T. Sagusa "Ring-opening Polymerization," Vol.I, Elsevier Appl. Sci. Publishers, London, pp. 121-183 (1984) hereinincorporated by reference. Preferred polyalkenylenes are derived fromC₅₋₁₂ cycloalkenes, with polypentenes, polydodecenylenes andpolyoctenylenes being particularly preferred.

Polyoctenylenes prepared in accordance with the methods disclosed in A.Draxler, Kautschuk and Gummi, Kunststoff 1981, pages 185 to 190 arepreferred. Polyoctenylenes having varying cis and trans double bondratios, varying J-values, and correspondingly varying molecular weightsare obtainable according to methods known from the literature.Polyoctenylenes having a viscosity number (J value) ranging from 50 to350 ml/g, preferably from 80 to 160 ml/g, measured in a 0.1% solution intoluene are preferred. 55 to 95%, preferably 75 to 85%, of the doublebonds are in the trans-form.

Known styrene homopolymers and/or impact resistant styrene polymers canbe added as additional components of the polyphenylene ether plasticmaterial. DE-OS 36 02 705 discloses suitable styrene polymers. Thestyrene polymer may be modified by incorporating an EP rubber, forexample, EPM rubber and EPDM rubber. Vulcanization agents and activatorsmay be used in such systems.

The EPM rubber is produced in the conventional manner by polymerizationof a mixture comprising 25-75% by weight ethylene and 75-25% by weightpropylene in the presence of a Ziegler-Natta catalyst, such as, e.g.,diethyl aluminum chloride.

The EPDM rubber is produced, analogously, by polymerization of a mixturecomprising more than 25% ethylene, more than 25% propylene and 1-10%, inparticular, 1-3%, of a diene. This diene should not be conjugated.Bicyclo(2,2,1)heptadiene, 1,4-hexadiene, dicyclopentadiene, andparticularly, 5-ethylidene-norborene are preferred. Suitable EPDMrubbers are produced under the trade name BUNA® AP (EPDM rubber) byBunawerke Huls GmbH, D-4370 Marl Germany.

Suitable peroxidic vulcanization agents are those peroxides known in theart for cross-linking, for example, EPDM rubbers, such as2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide,4,4-di-tert-butylperoxy-n-butylvalerate,1,1-di-tert-butylperoxy3,3,5-trimethylcyclohexane and in particularbis(tert-butyl-peroxyisopropyl)benzene. The use of these peroxidicvulcanization agents in preparing EPDM rubbers is described in thebrochure "Rubbery Chemicals-Crosslinking Peroxides" of Akzo Chemie(April 1985).

Suitable vulcanization activators include triallyl cyanurate (TAC),acrylates such as 1,4-butanediol-dimethacrylate (BDMA) andtrimethylolpropane trimethacrylate (TRIM). Particularly preferredvulcanization activators include TAC and/or BDMA.

If desired, the polyphenylene ether material may contain otherderivatives such as stabilizers, processing agents, foaming agents,metal fibers, rubber black, graphite, metal spangles, titanium dioxideand zinc sulfide. The weight ratio of reinforcing agents in thepolyphenylene ether material can vary anywhere from about 0% to about50%, that of the flame retardant up to about 15% and all other additivesto a total of about 5%, with respect to the total polyphenylene ethermaterial.

Preferably the polyphenylene ether plastic materials are produced bymixing the components in the melted state. At least one component iscompletely melted and the melt thus obtained is mixed with the othercomponents. Another possibility is to melt and mix all of the componentstogether. Melting temperatures typically range from about 250° C. toabout 350° C., in particular from about 260° C. to about 300° C., andcuring times typically range from about 0.3 to about 10 minutes, inparticular, from about 0.5 to about 3 minutes. Conventional equipmentfor processing highly viscous melts, not only in batch runs but also incontinuous operations, are suitable for melting and mixing. Twin-screwkneaders and co-kneaders are especially suitable. Other methods ofproducing the polyphenylene ether plastic materials are disclosed inU.S. Pat. No. 4,921,762, previously incorporated herein by reference.

Typical rubber constituents which bond effectively to such modifiedpolyphenylene ether plastic materials include, but are not limited to,rubbers such as SBR, natural rubbers, SBR/NR, BUNA® AP, EPDMJSBR, BUNA®EM, XNBR, IR, BUNA® SL, CB, Vi and AP, NR, IIR CiiR, and PNR, andmixtures thereof. The SBR and BR blends typically are crosslinked withsulphur or sulphur donors, and the EPDM blends typically employperoxides as vulcanization agents. The rubber material also may compriseconventional fillers, plasticizers, vulcanization agents, acceleratorsand the like.

A preferred modified rubber is a butadiene homopolymer adducted withmaleic anhydride. More preferably, the modified rubber materialcomprises 1,2-polybutadiene polymer adducted with maleic anhydride suchas that commercially available under the trade name RICO-BOND® 1031(maleic anhydride resin), CAS#25655-35-0, produced by Advanced Resins,Inc., Grand Junction, Colo. RICO-BOND® 1031 (maleic anhydride resin)serves as an adhesion promoter by imparting reactive carboxyl and esterlinkages and ethylenic unsaturation to the rubber material. RICO-BOND®1031 (maleic anhydride resin) may be used to modify other rubbers suchas BRS 1000, SBR, IR and the like.

The method of chemically bonding the two materials typically encompassesmolding the plastic material first, and then subjecting the rubber to aheat and/or pressure treatment or vulcanization in the presence of theplastic material. The solidification temperature of the plastic materialis preferably higher than the thermal treatment or vulcanizationtemperature of the rubber materials utilized. Therefore, the plasticmaterial does not degrade during the chemical bonding process. Skilledpractitioners are capable of determining injection molding operatingparameters for various plastics, rubbers, and modified plastics andrubbers.

Typically, the plastic material is prepared as described above, and thencompressed with an elastomeric thermoplastic, e.g., pressed together bypress curing, injection molding, or by extrusion. In the process, therubber material typically is heated to at least the temperature requiredfor thermal treatment or vulcanization. Suitable temperatures range fromabout 280° to about 550° F., and preferably from about 320° to about420° F. Skilled practitioners recognize that these temperatures vary forthe particular rubber employed as well as the various reactivefunctional groups employed. The treatment time required may vary withinthe range of from about 1 minute to about 15 minutes, and preferablyfrom about 3 minutes to about 7 minutes.

Other injection molding parameters useful in forming the plasticmaterial of the present invention are known to skilled practitioners inthe art. For example, skilled practitioners recognize the effect ofprocessing parameters and are capable of optimizing parameters such asinjection volume flow, filling time, injection speed, holding pressureand holding time. Skilled artisans recognize that the magnitude of theholding pressure influences shrinkage of the plastic material, sinkmarks and weight, and that the holding pressure should be high enough toavoid sink marks. It also is known that cooling time and temperatureaffect shrinkage and warpage and should be optimized to minimize theeffects. Finally, it is known that the properties of the plasticmaterial are predominantly determined during the filling phase, themechanical properties are affected by the batch temperature, andshrinkage and warpage typically occur during the holding or coolingphase.

Generally, in forming the chemical bond between the plastic and rubbermaterials, the injection molding, thermal treatment and vulcanizationconditions are optimized to form the strongest bond while minimizingadverse effects. For example, the formation of surface glaze on theplastic material should be avoided. Surface glaze can be eliminated bythorough drying of the granulated plastic material and by the use of avent in the extruder. Oxidation of the surface of the plastic materialalso should be presented. Oxidation of the surface can be eliminated bygrinding the surface of the plastic material before thermal treatment orvulcanization with the rubber material, or by use of a nitrogen blanket.The surface of the plastic material also should be adequately cleanedbefore thermal treatment or vulcanization with the rubber material. Thiscan be accomplished by use of aliphatic solvents and soap solutions.However, use of polar hydrocarbons such as aromatics andchlorohydrocarbons should not be employed to avoid deactivation of thefunctional groups on the plastic and rubber materials.

During the thermal treatment or vulcanization phase, movement betweenthe plastic and rubber materials should be avoided. Also, during hotmold removal, the rubber material should not be stretched, and duringthe cooling phase, the rubber and the plastic materials should not beallowed to shrink away from each other. Avoidance of these conditionswill ensure an adequate chemical bond between the rubber and plasticmaterials.

The plastic and rubber materials also may be chemically bonded in a onestep process known commonly under the names "co-extrusion", "one-stagetwo-color injection molding" and "two-component injection molding."Skilled practitioners are familiar with these methods and are capable ofadapting the processes to various plastic and rubber materials.

The plastic and rubber materials also may be chemically bonded to eachother wherein one of the materials is a fabric of natural and syntheticmaterials. For example, a relatively inelastic plastic material known asPEBAX® (polyether block amide), a polyester block amide available fromElf ATOCHEM N.A., Inc. (Elf Aquitaine), Philadelphia, Pa., has beenbonded to several relatively inelastic materials such as XNBR rubber,and various fabric materials such as polyester and cotton/polyesterblends. The fabrics and PEBAX® (polyether block amide) sheets were cutin about 8 inch squares. A sandwich of TEFLON® (tetrafluoroethylene)sheets and the materials was assembled as follows: First, a "9×15"TEFLON® (tetrafluoroethylene sheet) with a PEBAX® (polyether blockamide) sheet on top of the teflon sheet. A 9" square TEFLON®(tetrafluoroethylene sheet) covers approximately half of the PEBAX®sheet. The fabric material was then placed evenly over thePEBAX®/TEFLON® (tetrafluoroethylene) so that only half of the sheet isin direct communication with the PEBAX® (polyether block amide), andtherefore capable of bonding thereto. Aother 9" square of TEFLON®(tetrafluoroethylene) covers the other half of the fabric sheet. Thesandwich then is completely covered with another 9"×15" TEFLON®(tetrafluoroethylene) sheet.

The sandwich then was placed in a fabric bonding press at about 360° F.,the platen temperature was measured at between about 415° F. to about425° F., and the platen pressure set at about 75 psi. Two sets of PEBAX®(polyether block amide) sheets were tested, one being PEBAX® 3533(polyether block amide), and the other PEBAX® 5533 (polyether blockamide). The 3533 sandwich remained in the fabric press for about 3minutes whereas the 5533 sheets remained in the press for about 4minutes. The sandwiches then were cooled in a Carver platen press forabout 2 to about 3 minutes at about 2,000 psi.

Because only half of the sheets were bonded, a pulling test wasconducted where a variable load was placed on the half of unbondedfabric in the opposite direction to a load placed on the bonded fabric.The values represented in Table 1 below represent the load at which thematerials were separated.

When XNBR was used as the fabric material, the TEFLON®(tetrafluoroethylene) sandwich was not used. Rather, the materials werevulcanized at about 160° C. in a 2 Ton Rubber Press at about 1500 toabout 2000 psi for about six (6) minutes. The carboxylic acid groupspresent in the XNBR rubber reacted with PEBAX® (polyether block amide)material to form a strong chemical bond therebetween. When subjected tothe pulling test described above, the rubber material fractured, and thematerial was incapable of being separated at the bond juncture due tothe strong chemical bond formed between the XNBR rubber and PEBAX®(polyether block amide) materials.

The following Table 1 represents the maximum peeling load applied, andthe resulting peeling strengths achieved when the TEFLON® sandwichescomprising the PEBAX® (polyether block amide) material and fabricslisted were subjected to the peeling loads.

                  TABLE 1                                                         ______________________________________                                                                 Maximum   Avg. PeeI                                                           Peeling Load                                                                            Strength                                   Fabric Material                                                                              PEBAX     (lbs.)    (lbs./in.)                                 ______________________________________                                        Fine Glass Fabric                                                                            3533      5.3       3.4                                        Coarse Glass Fabric                                                                          3533      27.5      20.2                                       Fine Polyester Fabric                                                                        3533      33.6      27.5                                       Coarse Polyester Fabric                                                                      3533      19.7      14.7                                       Nylon Fabric   3533      10.5      6.8                                        50/50 Cotton/Polyester Blend                                                                 3533      7.3       4.9                                        Polyester Dipped in Adhesive                                                                 3533      31.9      25/5                                       Fine Glass Fabric                                                                            5533      4.5       2.8                                        Coarse Glass Fabric                                                                          5533      44.7      28.5                                       Fine Polyester Fabric                                                                        5533      30.9      24.4                                       Coarse Polyester Fabric                                                                      5533      13.4      9.1                                        Nylon Fabric   5533      17.7      12.1                                       50/50 Cotton/Polyester Blend                                                                 5533      7.3       4.5                                        Polyester Dipped in Adhesive                                                                 5533      31.7      22.5                                       ______________________________________                                    

As can be seen from the above table, it is possible to form a relativelystrong chemical bond which is resistant to fracture between a relativelyinelastic material such as PEBAX® (polyether block amide) and relativelyelastic materials such as glass, polyester and cotton fabric materials.Accordingly, an article of footwear can be manufactured wherein plasticmaterials are chemically bonded to the fabrics used in formulating theupper.

The following discussion pertains to various embodiments of the presentinvention utilizing chemically bonded plastic and rubber materials.

Referring to the drawings, wherein like numerals represent likeelements, shown in FIG. 1 is an outsole 24 comprising outsole segments26 a-d of a plastic material which are chemically bonded along desiredlines of flexion B--B, C--C, and D--D to rubber segments 22 a-c,respectively, forming rubber flex lines. A cross-sectional view of FIG.1 along line A-A is shown in FIG. 2 and shows rubber segments 22 a-cextending between independent outsole segments 26 a-d. Rather thanhaving independent outsole segments, it can be readily understood thatan alternate embodiment could comprise a footwear outsole 24 of aplastic material having a reduced profile or cross-section along orabout the desired line of flexion, e.g., a groove or channel, andeffectively substitute a more flexible rubber material for the lessflexible plastic material by filling in the grooves or channels withrubber material and bonding the rubber material to the plastic outsole24 to yield an outsole having a bottom perspective as shown in FIG. 1.

Shown in FIG. 2 (24) is a cross-sectional view along line A--A of thefootwear outsole 24 shown in FIG. 1 showing four separate outsolesegments 26a-d, substantially consisting of plastic material adjoiningrubber segments 22 a-c which are chemically bonded thereto. Thisconstruction permits greatly enhanced flexibility as compared toconventional outsole plates. In addition, it can be readily understoodthat rubber segments 22 a-c can be inclined relative to verticle toincrease bonding surface and affixed to the superior, or inferior,surfaces of outsole segments 26 a-d. It is further contemplated thathorizontal segments of rubber may be affixed either over horizontalplastic segments or under horizontal plastic segments, i.e. continuouspieces of rubber and plastic may be affixed to each other over theirfacing horizontal surfaces.

Shown in FIG. 3 is an alternate footwear outsole 24 comprising outsolesegments 26 a-c of a plastic material with rubber segments 22 a and bfor enhancing the flexibility of the footwear outsole 24 along selectarch lines of flexion E--E and F--F, respectively. One of the advantagesof this configuration is that the area of the outsole underlying theball of the forefoot is relatively undisturbed. This can facilitate theuse of an air bag (not shown), or other cushioning technology within theoverlying midsole (not shown) of an article of footwear. In addition,this configuration can facilitate the incorporation of select frictionaland traction characteristics to the area about the ball of the forefoot.

Shown in FIGS. 4a and b is an alternate footwear outsole 24 havingoutsole segments 26a-d of a plastic material underlying the forefoot andan outsole segment 26e being of either a rubber or plastic material. Theoutsole segments 26a-e which are chemically bonded to rubber segments22a-d which lay along desired arch lines of flexion E--E, F--F and G--G,and line H--H. The desired lines of flexion indicated by arch lines E--Eand G--G permit enhanced plantar flexion and dorsi flexion of thephalanges and corresponding digits or toes 42 a-e of a wearer's foot.This can facilitate enhanced performance in the sprinting eventsconducted in track and field and other speed orientated activities, orthose activities in which agility is a requirement. Further, the desiredline of flexion indicated by line H--H facilitates independent flexionof the medial and hteral digits or toes 42a, 42b, 42c, 42d, and 42e ofthe wearer's foot about the longitudinal axis, and in particular, thehallucis longus or first toe 42a with respect to the second 42b, third42c, fourth 42d, and fifth 42e toes of the foot. It can be readilyunderstood that the flexion afforded by line H--H could possibly beenhanced by further segmenting outsole segments 26c and 26d to provideadditional outsole segments, for example, outsole segments 26f and 26fas shown in FIG. 4c, accordingly. Further, a plurality of additionaloutsole segments (not shown) substantially parallel to the longitudinalaxis or line H--H, could be used in accord with the teachings of thepresent embodiment. In addition, segment 26c shown in FIGS. 4a and 4bcould be deleted and a continuous portion of rubber be used between archlines of flexion G--G and E--E. Likewise, segments 26c and 26f shown inFIG. 4c could be deleted and rubber substituted in their place. Bypermitting more extensive and independent use of toes 42a-e of the foot,a wearer can enjoy greater relative stability in an article of footwearincorporating such an outsole 24. The barefoot condition is known to beassociated with the lowest pronation and supination scores obtainedduring rearfoot motion analysis. Within conventional footwearconstructions, the toes 42a-e of the foot articulate within the confinesof a relatively inflexible article of footwear. Insofar as the shoeupper fits snugly about the forefoot, then little room exists for thetoes 42a-e to fully articulate. If more room is given for the toes 42a-eto articulate, then stability can become a problem as the foot may thenslide about within the article of footwear, a sort of "Catch-22," orno-win situation. The main problem is that the wearer's foot mustattempt to articulate and stabilize itseft in relation to the platformprovided by way of the insole (not shown), midsole (not shown), andoutsole 24 of an article of footwear. This platform is commonlyrelatively inflexible with respect to plantar flexion and dorsi flexionof toes 42a-e and respective metatarsalphalangeal joints, but even moreso with respect to like independent movement of medial and lateralportions of the ball and toes 42a-e found in the forefoot. In sum, as aresult of the homogenous and monolithic construction of conventionalarticles of footwear, and in particular, in the area of the forefoot,the natural abilities and capacities of the human foot can suffer unduelimitation. Further, the presence of rubber material and directcommunication with plastic outsole plate segments can serve to dampenshock and vibration caused by impact with a give supporting surface. Forexample, the artificial surfaces for running used in some track andfield facilities can be quite hard. In particular, the boards in thejumping events are of a reinforced and hardened wood construction andthe impacts associated with competition generate high levels of shockand vibration.

In addition, referring to FIG. 4c, please note that plastic outsolesegments 26c and f can include at least one permanent, or removabletraction element 60. As shown in FIG. 4c and cross-sectional view inFIG. 4d, plastic plate segment 26f, like 26c, is substantiallysurrounded by rubber material 22. The plantar surfaces of the foot, asshown in FIG. 4b, do not make substantial contact or impose high loadsupon plastic outsole segments 26c, nor plastic outsole segments 26c and26f as shown in FIGS. 4c and d. Therefore, when the forefoot loads thelarger spike plate shown in FIGS. 4c and d, a permanent projection, orremovable traction element 60 can cause plastic outsole segment 26f, andthe like to be deflected vertically towards the wearer's foot in thearea devoid of substantial plantar contact and support, as indicated byarea "C" in FIG. 4b. The rubber surrounding plastic outsole segment 26fis thereby placed in tension, and upon removal of the load will returnsegment 26f to its initial relatively planar orientation.

However, as the forefoot loads the outsole spike plate during thesupport phase, and in particular during the propulsion phase of therunning cycle, at least one of the toes 42a-e of the wearer's foot cangrip the plastic outsole segment 26f posterior to toes 42a-e which hasbeen momentarily deflected upwards. A grip or supporting surface isthereby provided against which the toes can perform useful workregarding the desired tasks of propelling the wearer (e.g. athlete)forward, but also balancing and stabilizing the foot. This embodimentwould be primarily intended for possible application in sprinting andfield events contested in track and field.

It can be readily understood that other means and methods can be appliedto the shoe upper, insole, midsole, and outsole 24, and the like, toenhance the flexibility of articles of footwear in keeping with themelting of this embodiment of the present invention.

Shown in FIG. 5 is an another embodiment of an outsole 24 according tothe present invention. The outsole 24 comprises outsole segments 26a andb of a plastic material and rubber segment 22 bonded to outsole segments26a and b for enhancing the flexibility of the footwear outsole 24 alonga select line of flexion I--I corresponding to the rearfoot strike zone(i.e., the area of initial contact with the ground for a usercharacterized as a rearfoot striker), of an article of footwear. Thisconfiguration can enhance cushioning and stability when the relevantstiffness of the cushioning materials used in select areas of theoverlying midsoles are selectively coordinated. In particular, thestiffness of the cushioning material or device used in segment 26bshould be reduced relative to that used in segment 26a. Further, themobility of segment 26b serves to effectively decrease the rear footangle and the length of a lever arm which can contribute to pronation.

Shown in FIG. 6 are a plurality of traction elements 50 substantiallycomprising rubber material which have been chemically bonded to threeoutsole segments 26a-c of a footwear outsole 24 which substantiallycomprise a plastic material. In addition, the three outsole segments26a-c are similarly connected by rubber segments 22a and b in accordancewith desired lines of flexion B--B and C--C as shown in FIG. 1.

Shown in FIG. 7 are a plurality of traction elements 50 substantiallycomprising plastic material which have been chemically bonded to threeoutsole segments 26a-c of a footwear outsole 24 which substantiallycomprise a rubber material. In addition, the outsole segments 26a-c areconnected by segments 22a and b in accordance with desired lines offlexion B--B and C--C as shown in FIG. 1. Segments 22a and b may be of aplastic material, or alternatively of a rubber material which ispreferably more flexible than that used in outsole segments 26a-c.

The foregoing embodiments have primarily dealt with narrow rubbersegments positioned along desired lines of flexion and connectingseparate outsole segments. Shown in FIG. 8 is an alternate footwearoutsole 24 embodiment having two outsole segments 26a and b of plasticmaterial substantially underlying the forefoot and rearfoot areas of thefoot which are chemically bonded to a rubber segment 22 whichsubstantially underlies the area of the midfoot. This configurationpermits enhanced flexibility, or torsional movement about thelongitudinal axis and thereby permits greater relative independentmovement between the rearfoot and forefoot.

Furthermore, in FIGS. 9-11, rather than bonding together separateoutsole segments, rubber segments 22 are bonded to an outsole plate 26to provide the desired flexibility.

In FIG. 9, there is shown an another embodiment of footwear outsole 24.The outsole 24 comprises an outsole plate 26 of a plastic material withrubber segments 22a-c having a wedge-shape chemically bonded to desiredvoid areas, e.g. v-shaped notches 28, of the outsole plate 26 forenhancing the flexibility of the footwear outsole 24 along select linesof flexion B--B and C--C. Alternatively, it can be readily understoodthat rubber segments 22 need not fully fill the voids in the outsoleplate 26 to achieve different degrees of flexibility. In addition, the"v-shaped" notches 28, and the like, can extend partially, orsubstantially across at least one portion of the outsole plate 26.Moreover, it can be readily understood that the select use of rubbermaterial and plastic material in a foot-wear outsole 24 can beconfigured so as to additionally comprise traction means.

Shown in FIG. 10 is another embodiment of an outsole 24. The outsole 26comprises an outsole plate 26 of plastic material having rubber segments22a and b chemically bonded in two portions to medial and lateral areasunderlying the midfoot. This configuration not only enhancesflexibility, or torsional movement about the longitudinal axis, but alsoprovides support to the medial longitudinal arch (line W--W), laterallongitudinal arch (line Y--Y), and transverse arch (line Z--Z) of thefoot.

Shown in FIG. 11 is another embodiment of an outsole 24. Herein, outsole24 comprises an outsole plate 26 formed of a plastic material showing aplurality of traction elements 50 comprising a rubber material which ischemically bonded to the plastic material of the outsole plate 26. Inaddition, rubber segment 22 fills a void or cavity of correspondingshape in the outsole plate 26 and is chemically bonded thereto. Therubber segment 22 is located substantially in the area underlying thecalcaneus of the foot for enhancing cushioning. It can be readilyunderstood that various midsole constructions utilizing plasticmaterials and rubber materials in a manner consistent with the teachingsdisclosed in FIG. 11 are contemplated and anticipated by this embodimentof the present invention.

Shown in FIG. 12 is a relatively conventional appearing footwear outsole24 comprising two outsole plates 22 and 26. Outsole plate 26 is of aplastic material in the area underlying the forefoot. Outsole plate 22is of a rubber material in three-quarter length. However, rather thanbeing adhesively bonded together, outsole plates 22 and 26 have beenchemically bonded to each other at their juncture 30.

Shown in FIG. 13a is a footwear outsole 24 fabricated conversely to theembodiment shown in FIG. 8. The areas of the outsole 24 underlying theforefoot (outsole plate 22a) and rearfoot (outsole plate 22b) aresubstantially comprised of rubber material and are bridged by an outsoleor moderator plate 26 comprising a plastic material which underlies thearea of the midfoot. In this embodiment, the moderate plate 26 overlapsand extends at least partially over the superior surface of the outsoleplates 22a and b which underlie the areas of the forefoot and rearfoot,respectively. This overlap shown in FIG. 13b relative to outsole plates22a and 26 provides a greater surface over which to provide a chemicalbond and provides a transitional area for the mechanical and elasticproperties of the outsole plates 22a to 26 to 22b.

Shown in FIG. 14 is a portion of an outsole 24 substantially consistingof rubber material to which has been chemically bonded a heel counter 53substantially consisting of plastic material along bond line 30 so as toform a one-piece unit. This construction is expected to enhance thestability of the heel counter 53.

In FIG. 15, there is shown the midfoot portion of a footwear outsole 24substantially consisting of rubber material having a hteral stabilityand support structure 51 substantially consisting of a plastic materialchemically bonded to the footwear outsole 24 about the hteral aspect ofthe area of the midfoot 37. It can be readily understood that likestability and support structures can be used about the forefoot,midfoot, or rearfoot areas, whether about the medial, lateral, anterior,or posterior aspects and whether in partial or complete combination.

Shown in FIG. 16 is a portion of an article of footwear 38 having afootwear outsole 24 substantially consisting of a rubber material andhaving a too guard 54 substantially consisting of a plastic materialchemically bonded to the outsole 24 along bond line 37. Thisconstruction can prolong footwear life by protecting the shoe upper (notshown) from excessive wear commonly experienced by users of articles offootwear, e.g., baseball pitchers or tennis players, who exhibit toedrag.

Shown in FIGS. 17a, 17b and 17c are various alternate embodiments of aremovable traction element 50 and, respectively, showing but a few ofthe possible combinations of rubber material and plastic material whichare possible and could be desired depending upon the situational demandsand environmental circumstances attending the use of an article offootwear. In FIG. 17a, the removable traction element 50a comprises athreaded screw component 40. A portion of the screw component 40 isanchored to a plastic core 20. The plastic core 20 has an outer layer 22of rubber material chemically bonded thereto on surface 51 thereof. Theplastic core 20 also has a ridge portion 42 to further aid in retainingthe outer layer 22 on the plastic core 20. The removable tractionelement 50c in FIG. 17c is like that of traction element 50a in FIG. 17awith the exception that the plastic core 20 has an exposed surface 44opposite the screw component 40.

In FIG. 17b, the removable traction element 50b comprises a threadedscrew component 40. A portion of the screw component 40 is anchored to abody portion 20 of a plastic material having a planar surface 51perpendicular to the main axis of the screw component 40 and oppositethereto. A traction layer 22 of rubber material is chemically bonded tothe planar surface 51. Alternatively, the body portion 20 may be of arubber material and the traction layer 22 may be of a plastic material.

Shown in FIG. 18 is an article of footwear 38 having a shoe upper 48 andincludes a strap 52 substantially consisting of plastic material. Thestrap 52 is chemically bonded to a footwear outsole 24 substantiallyconsisting of a rubber material along line 37. Alternatively, it can bereadily understood that a strap 52 consisting of rubber material can bechemically bonded to a footwear outsole 24 substantially consisting of aplastic material.

Shown in FIG. 19 is an article of footwear 38 having a shoe upper 48 andincludes a strap 52 substantially consisting of plastic material. Thestrap 52 is chemically bonded to a rubber strip 22 which serves as thepoint of origin, or anchor of the swap 52 and this rubber strip 22portion is in turn chemically bonded to a footwear outsole 24substantially consisting of a plastic material. This configurationpermits greater articulation of the footwear swap 52 and can therebyenhance the performance of the strap 52. In addition, the elasticproperties of the rubber strip 22 potion of the strap 52 can be utilizedto exert a preload upon the wearer's foot when the swap 52 is tightenedin such a manner as to stretch the rubber strip 22. In addition, therubber strip 22 present in the area about the origin of the strap 52 cansubstantially prevent fatigue and possible failure relative to a morerigid and inelastic plastic material of strap 52.

Alternatively, in FIG. 19, the shoe-upper 48 may be comprised of plasticfibrous material. Strap 52 may be of a rubber material with area 22deeming the area of chemical bonding of the strap 22 to shoe-upper 48.As a further alternative, strap 52 may be of plastic material chemicallybonded to a rubber strip 22 which in turn is chemically bonded to theshoe-upper 48, which is comprised of a plastic fibrous material.

Shown in FIGS. 20a and b are posterior and partial lateral views,respectively, of an article of footwear 38 showing a rearfoot strapconstruction showing substantially lateral and medially located heelcounters 53a and b substantially consisting of a plastic materialchemically bonded to a support strap 52 substantially consisting of arubber material which transits behind the posterior portion 55 of theshoe upper 48 and joins the lateral and medially located heel counters53a and b. It can be readily understood that other like structures arecontemplated for use in other portions of an article of footwear 38.Further, the anchor portions 56a, b, c, and d of heel counters 53a andb, respectively, may be chemically bonded to the sole 54 by appropriateselection of materials for the sole 54 at the point of contact.

Another embodiment of the present invention is shown in FIG. 21. In FIG.21, a portion of a footwear strap 52 having an eyelet insert 58 for shoelaces 57 is shown. The eyelet insert 58 substantially consisting of aplastic material for the passage, or affixing, of a shoe lace 57 ischemically bonded to the strap 52. This construction, and the like canextend the wear of a footwear strap 52 and permit better fit due to theelastic nature of the rubber material utilized for the strap 52.Moreover, this construction can introduce a preload when secured by awearer due to the elastic properties of the rubber material.

Shown in FIG. 22 is an article of footwear 38 having an articulatingshoe upper 48 substantially consisting of various segments of plasticmaterial which are chemically bonded to rubber material which serves toalign and form the various segments into a larger functional unit. Thiskind of construction can find application, e.g., in the footwear uppersof in-line roller skates, hockey skates or ski boots. The shoe upper 48includes a notched area "A" substantially comprising a more flexiblerubber or plastic material for permitting unrestricted plantar and dorsiflexion of the foot. Further, the shoe upper 48 includes a "floating" orsemi-mobile plastic 20 malleable guard for enhancing fit in the area ofthe ankles "B", but without compromising protection. In addition, theposterior heal portion is recessed and includes a plastic guard which isat least partially mobile so as to permit unrestricted plantar or dorsiflexion without impenging the Achilles tendon.

Shown in lateral view FIG. 23a and top view FIG. 23b is a stabilitydevice, e.g., a FOOTBRIDGER® (stability device) 47, comprising a plasticmaterial which has been chemically bonded to a footwear outsole 24substantially comprising a rubber material to form a one-piece unit.

Shown in FIG. 24 is a cross-sectional view along the anterior-posterioror longitudinal axis of an article of footwear 38 showing the use of amidsole moderator plate 33 comprising a plastic material which has beenchemically bonded to a footwear midsole 32 substantially comprising afoamed plastic or rubber material to form a one-piece unit.

The following examples illustrate the various techniques utilized inchemically bonding chemical and rubber materials together for use inoutsole for articles of footwear. Other features of the invention willbecome apparent in the course of the following description of exemplaryembodiments which are given for modification of the invention and arenot intended to be limiting thereof.

EXAMPLE 1

The following example exemplifies a particularly preferred embodiment ofthe invention wherein plastic and rubber materials are chemically bondedto form an outsole comprising mostly plastic materials with rubbermaterial flex lines. Embodiments of such an outsole are illustrated inFIGS. 1-5.

A single mold was constructed into which preformed plastic componentswere placed leaving spaces for the rubber flex lines. Plastic material(polyphenylene ether) was placed (preform) into the mold.

Unvulcanized rubber was then added to mold and molded using a 200 TonRubber Press machine. The molded article was vulcanized at 320° F. forabout 6 to about 8 minutes, and then was permitted to stand for about 4minutes and cool. The outsole comprising both plastic and rubbermaterials was removed from the mold and subjected to conventionalfootwear manufacturing techniques to produce an article of footwear.

EXAMPLE 2

A standard SBR rubber comprising 100 parts by weight SBR, 50 parts byweight RAF N330 Carbon black, 3.0 parts by weight zinc oxide, 1.0 partby weight stearic acid, 1.75 parts by weight sulfur, 0.7 parts by weightMBS and 0.9 parts by weight TBBS was modified by adding 3.0 parts byweight TBBS and 6 parts by weight RICO-BOND® 1031 maleic anhydrideresin. The SBR was modified by adding 3.25 parts per hundred rubber(PHR) TBBS and 8 PHR RICO-BOND® 1031 (maleic anhydride resin) to a tworoll mill and mixing the reactants at ambient to about 185° F. for about7 minutes or until a uniform dispersion is achieved. About 197 grams ofmodified SBR then was injected into a mold containing about 60 grams ofa preformed TPU-ABS blend in a 200 Ton Rubber Press at about 320° F. forabout 6 minutes, thereby permitting the formation of a chemical bondbetween the plastic and rubber material.

The material then was tested for pull strength--bond strength andcompared to rubber joined to plastic using conventional adhesivetechniques. The results demonstrate that the chemical bond formed inaccordance with the present invention is superior to mechanical bonds ofthe prior art.

EXAMPLE 3

A first sample was prepared wherein a 99 mm×20 mm×3.25 mm bar ofpolyethylene plastic was cut from a sheet of polyethylene plasticmaterial. A second sample was prepared wherein the same size bar ofpolyethylene was cut; however, a groove approximately 0.25 inches wideand 2 mm deep was cut in the center of the bar. A third bar having thesame dimensions as the first and second samples was prepared wherein athin strip of rubber material was placed between two polyethyleneplastic sheets. These were then placed into a 200 Ton Rubber Press atabout 320 to about 340° F. for about 4 to about 6 minutes in an ASTMtensile mold.

The three bars then were tested for resistance in kg to bending using a3-point loading system. Each bar was supported from below (2 pointsupport, 70 mm separation), then depressed in the center at 10 mm/minusing a long bar crosshead thereby creating a 3-point load on each bar.The resistance was measured in Kg/cm³ force. The results of thefollowing test are graphically shown in FIG. 25.

From FIG. 25, it can clearly be seen that the polyethylene bar which hada thin strip of rubber chemically bonded on both sides through itsmiddle showed the least amount of resistance per mm of deflection. Infact, the rubber-joined plastic bars were about 50 times more flexiblethan the plain plastic bar, about 10 times more flexible than thenotched plastic bar, and about 25 times more flexible than ahalf-thickness plain plastic bar.

Upon completion of the test, the notched bars retained a permanent crimpwhen the force was removed, and the plain plastic ban deformed slightly.The rubber-joined polyethylene bars, on the other hand, returnedcompletely to their original shape. Accordingly, rubber-joined plasticmaterials would possess significant advantages in flexibility overuniform or notched outsoles.

Numerous modifications and variations of the present invention may bepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described herein.

What is claimed is:
 1. An article of footwear comprising an outsolehaving heel, medial, forefoot and lateral areas, said outsole being abonded composite of relatively inelastic and relatively elasticmaterials wherein the relatively inelastic material comprises an outsoleplate and the relatively elastic material comprises a plurality ofsubstantially separate, independent segments underlying and chemicallybonded to only a portion of said outsole plate, and at least one of saidsubstantially separate, independent segments being positioned along atleast a portion of an outer perimeter of the outsole.
 2. The article offootwear according to claim 1 wherein the relatively elastic segments ofthe outsole are wedge-shaped and chemically bonded to desired void areasof the outsole plate for enhancing flexibility of the outsole alongselect lines of flexion.
 3. The article of footwear according to claim 2wherein at least one selected segment of relatively elastic materialextends substantially across at least a portion of the outsole.
 4. Thearticle of footwear according to claim 1 wherein at least one segment ofrelatively elastic material extends substantially across at least aportion of the forefoot area of the outsole.
 5. The article of footwearaccording to claim 1 wherein the relatively elastic segments arechemically bonded in at least two portions to medial and lateral areasof the outsole.
 6. The article of footwear according to claim 1 whereinthe relatively elastic segments of the outsole are arranged around theheel area of the outsole.
 7. The article of footwear according to claim6 wherein a further segment of relatively elastic material chemicallybonded to the outsole plate fills a cavity of corresponding shape in theoutsole plate, said cavity being centrally located in the heel area ofthe outsole.
 8. The article of footwear according to claim 1 wherein therelatively elastic segments are arranged long the perimeter of theoutsole in the heel, forefoot, medial and lateral areas of the outsole.9. The article of footwear according to claim 8 wherein at least onesegment of the relatively elastic material extends substantially acrossat least a portion of the outsole.
 10. The article of footwear accordingto claim 9 wherein at least one segment extends substantially across atleast a portion of the forefoot area of the outsole.
 11. The article offootwear according to claim 1, wherein said segments of relativelyelastic material comprise a rubber material selected from the groupconsisting of styrene butadiene rubber (SBR), natural rubbers (NR),styrene butadiene rubber/natural rubber (SBR/NR), ethylene propylenediene monomer/styrene butadiene (EPDM/SBR), carboxylated nitrile rubber(XNBR), polyisoprene rubber (IR), milliable urethane, polychloroporenes(neoprene), chlorosulfonated polyethylene, thermoplastic rubber, latex,and silicone rubber, and said relatively inelastic material comprises aplastic material selected from the group consisting of thermoplasticpolyurethane, polyamide, polyethylene, nitrile, polyvinyl chloride,ethylene vinyl acetate, polyester, polycarbonate, polypropylene,polyphenylene ether, styrene, vinyl, polyether block amide,tetrafluoroethylene, fluoropolymers, thermoplastic polyester,chlorosulfonated polyethylene and polycarbonates.
 12. The article offootwear according to claim 11, wherein said relatively elastic materialis modified with a maleic compound selected from the group consisting ofmaleic acid, maleic anhydride, half alkyl ester of maleic acid, maleicamide and maleic imide.
 13. The article of footwear according to claim11, wherein said relatively inelastic material is modified with afunctional moiety selected from the group consisting of an amine, ahydroxyl group, a thiol group, a carboxyl group, an isocyanide group, anepoxy group, an ether group, an aldehyde group, a borane group, asilicon group and groups derived therefrom such as a urethane group, anester group, an amide group, an ammonium salt group and a metalcarboxylate group.
 14. The article of footwear according to claim 1,wherein said relatively inelastic material comprises a material selectedfrom the group consisting of styrene butadiene rubber (SBR), naturalrubbers (NR), styrene butadiene rubber/natural rubber (SBR/NR), ethylenepropylene diene monomer/styrene butadiene (EPDM/SBR), carboxylatednitrile rubber (XNBR), polyisoprene rubber (IR), milliable urethane,polychloroporenes (neoprene), chlorosulfonated polyethylene,thermoplastic rubber, latex, and silicone rubber, and said relativelyelastic material comprises a material selected from the group consistingof thermoplastic polyurethane, polyamide, polyethylene, nitrile,polyvinyl chloride, ethylene vinyl acetate, polyester, polycarbonate,polypropylene, polyphenylene ether, styrene, vinyl, polyether blockamide, tetrafluoroethylene, fluoropolymers, thermoplastic polyester,chlorosulfonated polyethylene and polycarbonates.
 15. The article offootwear according to claim 14, wherein said relatively inelasticmaterial is modified with a maleic compound selected from the groupconsisting of maleic acid, maleic anhydride, half alkyl ester of maleicacid, maleic amide and maleic imide.
 16. The article of footwearaccording to claim 14, wherein said relatively elastic material ismodified with a functional moiety selected from the group consisting ofan amine, a hydroxyl group, a thiol group, a carboxyl group, anisocyanide group, an epoxy group, an ether group, an aldehyde group, aborane group, a silicon group and groups derived therefrom such as aurethane group, an ester group, an amide group, an ammonium salt groupand a metal carboxylate group.
 17. The article of footwear according toclaim 1, wherein said outsole plate comprises polyether block amide andsaid segments comprise carboxylated nitrile rubber (XNBR).
 18. Thearticle of footwear according to claim 8, wherein said outsole platecomprises polyether block amide and said segments comprise carboxylatednitrile rubber (XNBR).
 19. The article of footwear according to claim10, wherein said outsole plate comprises polyether block amide and saidsegments comprise carboxylated nitrile rubber (XNBR).
 20. An article offootwear comprising an outsole defined by an outer perimeter and havingheel, medial, and forefoot areas, said outsole comprising a polyetherblock amide outsole plate overlying and chemically bonded to a pluralityof substantially separate, independent segments of carboxylated nitrilerubber (XNBR), said substantially separate, independent rubber segmentsbeing chemically bonded to only a portion of the outsole plate andarranged such that at least one segment extends substantially across atleast a portion of the forefoot area of the outsole and at least twofurther segments, one on either side of the medial area of the outsole,extend from opposite portions of the outsole perimeter toward a centralportion of the medial area, and such that at least one segment extendssubstantially along the perimeter of the outsole around the heel area.